ON - is used for location, for example, the dog is on the table.
ONTO - is used with movement, for example, the dog jumped onto the table; but a lot of people will say "the dog jumped on the table" because it's shorter.
This blog is mainly to explain a different English language expression every day. Sometimes I post other stuff. I also have a YouTube channel which is mostly about computer software: https://www.youtube.com/englishspacedog
